Custom Cursors - how can I change the position / offset of the image?

Hi all.
Using Any way to Unset cursor (HTML5) Pano's as a basis, I'm trying to set a custom cursor for my panoramic video.. I'm curently doing:

<cursors	
    standard="url('../cursor.png'), move"
    dragging="url('../cursor.png'), move"
    moving="url('../cursor.png'), move"
/>

…which is working fine except the image is anchored at the top left. What I'd like is for the mouse pointer to be the middle of the image as it's not the best experience otherwise. Looking in the docs I couldn't find anything at all on this, is there a way I can do it?

Thanks in advance :)